Valve cover plug

This may not be a "nailhead only" question. I am finishing a '65 401 which I am installing in my '66 Skylark GS convertible (engine now red, BTW). Where can I find a replacement plug for that 1 1/4" hole in the steel valve cover? The original is hard, puffed outward and cracked. I have found body plugs, but I think they are too thin. Any thoughts?

This is the hole where the tube to the air cleaner would go if it was a '66 engine.

Thanks in advance,

 

CARS sells them........I also think STEELE rubber products has them too. :TU:

 

Thanks, Joe. I haven't been able to find it in their on-line catalog, so I'll give them a call.